Unknown,Transcriptomics,Genomics,Proteomics

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Characterization of Directly Regulated Thyroid Hormone Mediated Gene Expression Following Short-Term Perturbations in Thyroid Hormone Levels in Juvenile Mice

ABSTRACT: We investigated the effects of thyroid hormone disruptions on gene expression in juvenile mice liver to develop a stronger understanding of the mechanisms by which thyroid disrupting chemicals impair development. Gene expression was examined by hybridization of hepatic RNA to Agilent mouse microarrays for hyper-, hypo-, hypo-replacement (hypo+) and euthyroid animals. Keywords: Toxicogenomics, biomarkers of thyroid disruptors Hypothyroidism was induced from post natal day (PND) 13 to 15 by adding model thyroid toxicants methimazole and sodium perchlorate to drinking water of pregnant females. Hyperthyroidism was induced by intraperitoneal injections (i.p.) of THs at PND 15, 4 hours before decapitation and tissue collection. For the hypothyroid/replacement group; dams were provided with drinking water for 3 days (PND 13 to 15), containing a mixture of methimazole/sodium perchlorate. Pups then received intraperitoneal injections of thyoid hormones on PND 15, 4 hours before decapitation and tissue collection.

ORGANISM(S): Mus musculus

SUBMITTER: Morie Malowany

PROVIDER: E-GEOD-21307 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Thyroid hormone-regulated gene expression in juvenile mouse liver: identification of thyroid response elements using microarray profiling and in silico analyses.

Paquette Martin A MA Dong Hongyan H Gagné Rémi R Williams Andrew A Malowany Morie M Wade Mike G MG Yauk Carole L CL Yauk Carole L CL

BMC genomics 20111229

<h4>Background</h4>Disruption of thyroid hormone signalling can alter growth, development and energy metabolism. Thyroid hormones exert their effects through interactions with thyroid receptors that directly bind thyroid response elements and can alter transcriptional activity of target genes. The effects of short-term thyroid hormone perturbation on hepatic mRNA transcription in juvenile mice were evaluated, with the goal of identifying genes containing active thyroid response elements. Thyroid ...[more]

PMID: 22206413

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Project description:MicroRNAs (miRNAs) are extensively in diverse biological processes. However, very little is known about the role of miRNAs in mediating thyroid hormones (TH) action. Maintenance of appropriate TH levels is known to be critically important for development, differentiation and maintenance of metabolic balance in mammals. We induced transient hypothyroidism in juvenile mice by short term exposure to methimazole and perchlorate from post natal day (PND) 12 to 15. The expression of miRNAs in the liver was analyzed with the Taqman Low Density Array (containing up to 600 rodent microRNAs). We found the expression of 40 miRNAs was significantly altered in the liver of hypothyroid mice compared to euthyroid controls. Among the miRNAs, miR-1/206/133 exhibited a massive increase in expression (50 – 500 folds). To further explore TH effect on miR-1/206/133, we treated mouse hepatocyte AML 12 cells with 10 nm T3 for 1 hr and 24 hrs. TH treatment induced the down-regulation of miR-1/206/133b at both time points, reaching statistical significance at 24 hrs. To identify the genes targeted by these miRNAs, DNA microarrays were used to examine hepatic mRNA levels in the hypothyroid mouse model alongside controls. We found transcripts from 92 known genes were significantly altered in hypothyroid mice. Web-based target predication softwares (TargetScan and Microcosm) identified 14 of these transcripts as targets of miR-1/106/133. The vast majority of these mRNA targets were significantly down-regulated in hypothyroid mice, corresponding well with the up-regulation of miR-1/206/133 in hypothyroid mouse liver. The results suggest that TH regulation of these genes may occur secondarily via the reduced repression consequent to TH-induced down-regulation of miR-1/206/133. These studies provide novel insight into the role of miRNAs in mediating TH regulation of gene expression. Agilent two-color microarray were used to perform gene expression profile in euthyroid and hypothyroid male mouse livers, 5 biological replicates. TLDA (Taqman microRNA Array) was used to explore the miRNA expression profile in euthyroid and hypothyroid male mouse livers, 4 biological replicates.

Project description:In the present study we investigate the effect of maternal pulmonary exposure to titanium dioxide (UV-Titan designed for use in the paint and lacquer industry) on prenatally exposed offspring. Time-mated mice (C57BL/6BomTac) were exposed by inhalation for 1 h/day to 42 mg UV-titan/m3 aerosolized powder or filtered air during gestation days (GD) 8-18. We evaluated levels of DNA strand breaks using the comet assay in bronchioalveolar lavage (BAL) cells and liver cells of the time-mated mice, and in liver cells of the offspring. In parallel, we analyzed changes in gene expression in the liver tissue of offspring using DNA microarrays. We demonstrate that UV-Titan did not induce DNA strand breaks in the time-mated mice or their offspring. Transcriptional profiling of newborn liver tissue revealed changes in the expression of genes related to the retinoic acid (RA) signalling pathway in the females, while gene expression in male offspring was relatively unaffected by exposure. Time-mated, nulliparous mice (C57BL/6BomTac, Taconic Europe, Ejby, Denmark) were exposed to filtered clean air or approximately 42 mg/m3 UV-Titan on GD 8M-bM-^@M-^S18 for 1 hr/day by a whole-body exposure.Delivery was expected on GD 20, and designated postnatal day (PND) 0. On PND 2, one offspring (M-bM-^@M-^\newbornM-bM-^@M-^]) per litter was killed by decapitation, to yield litters with at least 5 offspring per exposure group. The newborn offspring were collected two days after birth. On PND 23-24 (M-bM-^@M-^\at weaningM-bM-^@M-^]) one male and one female per litter were killed. Organs were dissected, weighed, placed in NUNC cryotubes, snap frozen in liquid N2 and stored at -80M-BM-0C until analysis. Exposed dams were killed on PND 24-25 (26-27 days after last exposure). DNA strad break detection was carried out in bronchoalveolar lavage fluid in dams by COMET assay. Total RNA was extracted from offspring livers and gene expression profiling was carried out on whole liver tissues from offspring. 9 UV-Titan treated and 7 controls mice consisting of 8 males and 8 females mRNA, hepatic, developmental, Toxicogenomics, nano-titanium dioxide

Project description:Although the effects of thyroid hormones (TH) on the brain development have been extensively studied perinatally, effects of TH of maternal origin on the fetal brain development have been largely unexplored. We applied a high throughput study on the mouse models with aberrant TH levels on gestation day (GD) 16, before the onset of fetal thyroid function. Although 3 day treatment with methimazole (MMI) and perchlorate significantly decreased TH levels in fetal cerebral cortex, few changes in the abundance of mRNA were revealed by the microarray analysis. Injection TH to dams 12 hours before sacrifice on GD 16 induced 161 genes significantly changed in fetal cortex. Nine out of 10 selected genes were confirmed with RT-PCR, including known TH responsive gene Klf9 and other novel TH responsive genes such as Appbp2, Ppap2b and Fgfr1op2. TH regulation of the expression of these genes was also confirmed with cultured N2a? cells. Thyroid responsive elements (TREs) in the promoters of these genes were identified using electrophoresis mobility shift assay. TH effect on microRNA (miRNA) expression in developing cortex on GD 16 and postnatal day (PND) 15 was investigated with microarray and RT-PCR. Some of miRNAs and precursors decreased in fetal cortex from the dams injected with TH on GD 16, including miR-16 and miR-106. Using 3’ untranslate region reporter vector, we identified Klf9 is one of the target genes of miR-106, while Ppap2b is the target of miR-16. These results indicated that TH regulation on gene expression could through TR-TRE interaction and through regulating target miRNA expression. This study is the first report to identify TH responsive genes and miRNAs genome wide in the early fetal brain; it provides evidence to further understand the mechanism of TH effect on brain development. Timed-pregnant C57BL/6 mice (n=20; Harlan, Indianapolis, IN) arrived on gestational day (GD) 11 and were housed individually in plastic cages under a 12:12 light cycle (0600 h–1800 h) with food available ad libitum. Mice were divided randomly into one of 4 groups (control, hypo, hypo+ and hyper; 5 per group) . Mice in the control and hyper groups were provided with fresh drinking water containing 2% sucrose from GD 13 to GD 16 until sacrifice. Mice in hypo and hypo+ were provided with fresh drinking water daily containing 1% Perchlorate (Per) and 0.025% Methimazole (MMI) supplemented with 2% sucrose (to mask bitterness) from GD 13 to sacrifice on GD 16. Twelve hours prior to sacrifice on GD 16 all mice received a single subcutaneous injection. Control and hypo mice received vehicle (0.9% saline in 100 µl volume); the hypo+ group received 25.0 µg/100g body weight thyroxine (T4) with 2.5 µg/100g body weight T3 to restore a physiological level of TH; the hyper group received 100.0 µg/100g body weight T4 with 10.0 µg/100g body weight T3 to model hyperthyroidism. Dams were killed by exposure to CO2. Fetuses were dissected from the uterine horn and embryonic membranes then frozen on pulverized dry ice. Tissue samples were taken from the fetuses to determine sex using PCR for SRY (Yang J and RT Zoeller, 2002). Fetal cerebral cortices were removed from each mouse and used for microarray and RT-PCR analysis. Total RNA was extracted from half cortices of individual female fetuses using RNeasy Lipid tissue Mini kits (Qiagen, Germantown, MD) according to the manufacturer's instructions. The quality of total RNA was evaluated by A260/A280 ratio (found to be at least 1.8 for each sample) and by electrophoresis on the Agilent Bioanalyzer. The Yale Center for the Neuroscience Microarray Consortium carried out the Affymetrix microarray analysis using The GeneChip Rat Genome 230 2.0 Array. Preparation of labeled cRNA for hybridization onto Affymetrix GeneChips followed the recommended Affymetrix protocol. Control versus each of the three treatment groups: hyper, hypo, and hypo+. 1 of 20 samples removed due to poor quality.

Project description:Polycyclic aromatic hydrocarbons (PAHs) are widely distributed, carcinogenic environmental contaminants produced as a consequence of the incomplete combustion of fossil fuels. Benzo[a]pyrene (BaP) is a very extensively studied prototypical PAH. We recently reported a complete lack of change in microRNA (miRNA) expression in adult mouse liver following oral gavage with BaP despite a robust transcriptome response. We hypothesized that hepatic miRNAs may not be highly responsive to the treatment. Here, we analyse the pulmonary mRNA and miRNA response to BaP in the same mice. Adult male B6C3F1 mice were exposed to 5, 50, 150 and 300 mg/kg BaP by oral gavage for three consecutive days and sacrificed 4 or 24 hours after the last exposure. Serum clinical chemistry and DNA adduct levels in whole lung and liver tissues were analysed at both the time points for all the doses. Acute exposure to BaP resulted in modest decreases in serum inorganic phosphorous, calcium, glucose, alkaline phosphatase and lactate dehydrogenase in animals treated with 300 mg/kg BaP. 32P postlabeling of DNA revealed similar increases in BaP-DNA adducts in both lungs and livers of exposed mice in a dose dependent manner at the 4 hour time point. Using DNA microarrays, pulmonary mRNA and miRNA expression was analysed 4 hours after the final exposure. Over 1,000 genes were statistically differentially expressed (fold change > 1.5 and p < 0.05), encompassing numerous pathways including: oxidative stress, xenobiotic metabolism, cell proliferation, cell cycle, B and T-cell receptor signalling and primary immunodeficiency signalling pathways. Analysis of miRNA profiles revealed downregulation of miR-150, miR-142-5p, 142-3p and upregulation of miR-34c and miR-29b. These miRNAs are involved in various biological processes including immune response, cell proliferation and cell cycle, which are also the main pathways affected at the gene expression level. As BaP exposure does not result in hepatocarcinogenicity, but does cause lung cancer, these miRNAs may play an important role in the outcome of the exposure and be more predictive of carcinogenesis. Keywords: mRNA, miRNA, Pulmonary, non-target tissue, Toxicogenomics, Benzoapyrene Adult male B6C3F1 mice were exposed to 5, 50, 150 and 300 mg/kg BaP by oral gavage for three consecutive days and sacrificed 4 or 24 hours after the last exposure. Serum clinical chemistry and DNA adduct levels in whole lung and liver tissues were analysed at both the time points for all the doses. Using DNA microarrays, pulmonary mRNA and miRNA expression was analysed 4 hours after the final exposure. This submission only contains the 4hr time point, at control, 150mg/kg and 300mg/kg (except for the liver study where only the control and 300mg/kg samples were used).

Dataset Information

Characterization of Directly Regulated Thyroid Hormone Mediated Gene Expression Following Short-Term Perturbations in Thyroid Hormone Levels in Juvenile Mice

Publications

Thyroid hormone-regulated gene expression in juvenile mouse liver: identification of thyroid response elements using microarray profiling and in silico analyses.

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